Processes for manufacturing such a composite component are already known, from Document FR-A-2,474,395, which comprise the steps consisting in:
making separately a set of individual plies, each individual ply being obtained by arranging rods of resin-impregnated fibers, preserved in the non-rigidified state, side by side in a manufacturing mould, the said rods of fibers having ends arranged between cut pieces consisting of layers of resin-impregnated fibers, the ply then being rigidified under pressure by heating followed by cooling: PA1 assembling several individual plies in order to form a bundle of approximately uniformly spaced rods; PA1 encasing at least the rods of fibers with at least one elastomer; and PA1 curing the injected elastomer in order to form the composite component capable of flexing and twisting. PA1 the ends of the rods have a cross-section of quadrangular shape, the rods having central parts joined to the ends by transition zones such that the surface area of the cross-section of the rods is constant and the length of the transition zone is very small compared to that of the rods; and PA1 the cut pieces consisting of layers of fibers, arranged on each side of the ends of the rods, comprise fibers oriented at more or less 45 degrees to the longitudinal fibers of the said rods. PA1 the step consisting in encasing at least the rods comprises introducing at least one elastomer into each of the rigidified plies before assembling these plies together; PA1 the step consisting in encasing at least the rods comprises alternately stacking rigidified plies and layers of at least one elastomer; PA1 several elastomers, having different modulus, damping and environmental-resistance properties, are used; PA1 the step consisting in encasing at least the rods comprises individually sheathing each rod with an elastomer; PA1 the step consisting in encasing at least the rods comprises injecting an elastomer into the said bundle; PA1 the elastomer is injected into the said bundle in the viscous state; PA1 the resin used is a thermoplastic resin and the heating which helps to rigidify each ply is carried out at a melting temperature of the thermoplastic resin. Advantageously, the resin used makes it possible to carry out complete or localized successive shapings and consolidations during the manufacture of the component by successive meltings of the resin; PA1 the step consisting in assembling several individual plies comprises melting the impregnation resin of the ends of the individual plies; PA1 the step consisting in assembling several individual plies comprises the steps consisting in interposing films or powder of a thermoplastic resin between ends of the individual plies and then in pressing and heating the ends of the individual plies in order to melt the thermoplastic resin; PA1 the step consisting in assembling several individual plies comprises the thermocompression bonding of the ends of the individual plies, an adhesive material being interposed between the ends of the said plies; PA1 the rods and the cut pieces comprise carbon fibers and/or glass fibers; PA1 the thermoplastic resin in which the rods and the cut pieces are embedded are of the polyetherether-ketone type called PEEK melting at approximately 380.degree. C.; PA1 the films or the powder which are interposed between the ends of the individual plies are made of a thermoplastic resin of the PEEK type; PA1 the said adhesive material interposed between the ends of the individual plies is a thermoplastic resin of the polyetherimide type called PEI melting at approximately 300.degree. C.; PA1 the central parts of the rods have a circular cross-section and the cut pieces arranged on each side of the ends of the rods cover the transition zones, there being at least three pieces comprising, from the outside of the component to the rods, a solid cut piece, a cut piece having notches whose sides converge towards the inside of the said piece, and a cut piece having rectangular openings parallel to the central part of the rods, the said openings and the said notches lying opposite the transition zone of the rods; PA1 the rectangular openings and the notches are intended to be filled with a filling film made of a thermoplastic resin; and PA1 the two ends of the stacked individual plies are pressed and heated one after the other in order to minimize the deformations of the central parts of the rods, the region of the transitions zones optionally being cooled, by blowing a gas, in order to avoid crushing the rods at the ends and to avoid deforming them in the central part.
In this process of the prior art, the step consisting in encasing at least the rods of fibers with at least one elastomer consists in injecting a single type of elastomer after having formed the bundle. This process does not make it possible to manufacture a component capable of twisting which has different characteristics depending on the functionalities of each of the regions of the bundle capable of twisting. Placing the rods of fibers in the mould requires means for positioning them inside this mould so as to obtain the optimum placement of the rods with respect to one another. However, this type of mould is expensive to manufacture.
In addition, the resin used is a thermosetting resin such as an epoxy.
Thermosetting resins are characterized by the fact that they cure by crosslinking or polymerizing, this constituting irreversible curing.
This irreversible curing means that the elastomeric arm capable of twisting and flexing is difficult to manufacture since the arm is made by complete or localized successive shapings and consolidations, and since it is impossible to compensate for or correct any manufacturing imperfection or imprecision, and hence there is a high scrap rate.